A resolver (as in “resolution”) is an electro-mechanical device for decoding an angular-rotating position and translating it into digital information to be used in required calculations and for controlling other systems.
An analogous resolver measures the rotating angle by exporting voltage or current without any need for brushes. It looks like a motor and is composed of coils, a rotor and a stator. Normally the resolver will include three coils, which result in a precision of five degrees, yet the more coils in the resolver, the higher the precision.